Optical structure having polymer-covered protrusions contacting bandpass filter

Abstract

An optical structure is provided. The optical structure includes a sensor, a bandpass filter and a plurality of protrusions. The bandpass filter is disposed above the sensor. The protrusions are disposed on the bandpass filter. The bandpass filter allows light with a wavelength of 700 nm to 3,000 nm to pass through. The protrusions have a size distribution that controls the phase of the incident light to be between 0 and 2π.

What is claimed is: 
     
       1. An optical structure, comprising:
 a sensor, comprising a semiconductor substrate and a plurality of photoelectric conversion units disposed in the semiconductor substrate; 
 a first bandpass filter disposed above the plurality of photoelectric conversion units of the sensor, wherein first bandpass filter comprises SiH, SiGe, GeH or a combination thereof; 
 a plurality of first protrusions disposed on and directly contacted with the first bandpass filter; 
 a first polymer layer covering the first bandpass filter and the plurality of first protrusions; and 
 an encapsulation material bonded on the semiconductor substrate of the sensor and disposed between the semiconductor substrate of the sensor and the first bandpass filter; 
 wherein each of the plurality of first protrusions includes a first end surface directly contacted with the first bandpass filter and a second end surface directly contacted with and not exposed from the polymer layer; 
 wherein a refractive index of the plurality of first protrusions is higher than a refractive index of the first polymer layer. 
 
     
     
       2. The optical structure as claimed in  claim 1 , wherein the sensor comprises a CMOS image sensor or a fingerprint sensor. 
     
     
       3. The optical structure as claimed in  claim 1 , wherein the first bandpass filter allows light with a wavelength of 700 nm to 3,000 nm to pass through. 
     
     
       4. The optical structure as claimed in  claim 1 , wherein the plurality of first protrusions comprise cylinders, hexagonal pillars or square pillars, at least one of the plurality of first protrusions comprises a first portion and a space surrounded by the first portion, and the at least one of the plurality of first protrusions further comprises a second portion surrounded by the space. 
     
     
       5. The optical structure as claimed in  claim 1 , wherein the plurality of first protrusions are cylinders, and each of the protrusions has a diameter of 150 nm to 300 nm. 
     
     
       6. The optical structure as claimed in  claim 1 , wherein the plurality of first protrusions have a pitch of 100 nm to 1,000 nm. 
     
     
       7. The optical structure as claimed in  claim 1 , wherein the plurality of first protrusions have a size distribution that controls a phase of an incident light to be between 0 and 2π. 
     
     
       8. The optical structure as claimed in  claim 1 , further comprising an anti-reflective layer disposed on the first polymer layer. 
     
     
       9. The optical structure as claimed in  claim 1 , wherein the semiconductor substrate of the sensor is connected to a printed circuit board by wire bonding. 
     
     
       10. The optical structure as claimed in  claim 1 , wherein the semiconductor substrate of the sensor is connected to a printed circuit board by solder balls. 
     
     
       11. The optical structure as claimed in  claim 1 , wherein the plurality of first protrusions comprise a high-refractive-index material with a refractive index of 3.0 to 5.0. 
     
     
       12. The optical structure as claimed in  claim 11 , wherein the plurality of first protrusions comprise TiO 2 , SiN, SiO 2 , SiH or a combination thereof. 
     
     
       13. The optical structure as claimed in  claim 1 , further comprising a low-refractive-index material layer disposed between the semiconductor substrate of the sensor and the first bandpass filter. 
     
     
       14. The optical structure as claimed in  claim 13 , further comprising a second polymer layer disposed between the low-refractive-index material layer and the first bandpass filter. 
     
     
       15. The optical structure as claimed in  claim 14 , further comprising a plurality of second protrusions disposed in the second polymer layer. 
     
     
       16. The optical structure as claimed in  claim 1 , further comprising a glass substrate having a thickness of 50 μm to 500 μm disposed between the semiconductor substrate of the sensor and the first bandpass filter, wherein the first bandpass filter is disposed on a top side of the glass substrate. 
     
     
       17. The optical structure as claimed in  claim 16 , further comprising a second bandpass filter disposed on a bottom side of the glass substrate. 
     
     
       18. The optical structure as claimed in  claim 16 , wherein there is a space between the semiconductor substrate of the sensor and the glass substrate. 
     
     
       19. The optical structure as claimed in  claim 18 , further comprising a low-refractive-index material, a normal-refractive-index material or a combination thereof filled in the space.